This invention relates to organopolysiloxane polymers and more particularly to phenyl-containing organopolysiloxane fluid polymers.
In the past, there were three major types of silicone polymers which comprise nearly all of the phenyl-containing organopolysiloxanes. These included (1) those siloxanes with phenyl and methyl groups on the same silicon atom, (2) those siloxanes with two phenyls on one silicon and two methyls on the next or subsequent silicon atoms, and (3) those siloxanes containing phenyl tri units stopped with trimethyl units.
An example of the first type includes polymers of the structure ##STR2## wherein Ph is phenyl and wherein, in general, x=0.05 y to y=0.
The second major type includes those polymers having the structure, ##STR3## where Ph is phenyl and wherein, in general, x=0.05 to x=y.
The third group of polymers has the structure ##STR4## wherein the polymer length varies up to about 25 phenyl containing units.
For various reasons, these prior art silicone fluids are characterized with both technical and commercial problems. For example, the first of the above-identified silicone fluids are necessarily made from a starting material, i.e., methylphenyldichlorosilane, which comes from an expensive Grignard process while the polymers associated with the other above-identified classic structures are characterized with processing problems. For example, those polymers containing both diphenyl and dimethyl units have been found to be excessively volatile and moreover are difficult to manufacture in low viscosity form which is oftentimes desirable.
The uses for these hereinabove described silicone polymers are of course widespread, depending upon molecular weight and structure, and are well known. Included among these uses are, for example, lubricity additives for plastics, high temperature grease components and general mechanical fluids.
More specifically, one recently significant use of phenyl-containing organopolysiloxane fluids has been as internal mold release agents in polycarbonates. See, for example, U.S. Pat. No. 3,751,519. However, prior art phenyl organopolysiloxane fluids have not been totally satisfactory for polycarbonates as a result of their low solubility in the polycarbonate. Moreover, transparency usually desired in polycarbonate products is usually lost when these prior art phenyl-containing organopolysiloxane fluids are added thereto.